Wavelength-polarization-multiplexed multichannel perfect vortex array generator based on dielectric metasurface.

The multi-channel perfect vortex (PV) array based on metasurface has important applications in optical communication, particle manipulation, quantum optics, and other fields due to its ultra-thin structure and excellent wavefront control ability. However, it is very challenging to utilize a single metasurface to simultaneously achieve independent channel PV arrays at different wavelengths with low crosstalk and low structural complexity. Here, we propose and design a single rectangular structured metasurface based on TiO2, achieving a multi-channel PV beam array with dual-wavelength and dual-polarization multiplexing. Simulation and experimental results show that when two orthogonal linearly polarized beams with wavelengths of 532 nm and 633 nm are incident on the metasurface, clear PV arrays with corresponding topological charge arrangements can be obtained in different diffraction regions of the same observation plane. The metasurface proposed in this article can enhance the channel capacity of a PV beam array through wavelength-polarization-multiplexing, thus having important application potential in spatial information transmission, high-dimensional information storage, and secure information encryption.

Degradation mechanisms and toxicity determination of bisphenol A by FeOx-activated peroxydisulfate under ultraviolet light.

Ultraviolet light (UV)-assisted advanced oxidation processes (AOPs) are commonly used to degrade organic contaminants. However, this reaction system's extensive comprehension of the degradation mechanisms and toxicity assessment remains inadequate. This study focuses on investigating the degradation mechanisms and pathways of bisphenol A (BPA), generation of reactive oxygen species (ROS), and toxicity of degradation intermediates in UV/PDS/ferrous composites (FeOx) systems. The degradation rate of BPA gradually increased from the initial 11.92% to 100% within 120 min. Sulfate radicals (SO4.-), hydroxyl radicals (.OH), superoxide anions (O2.-), and singlet oxygen (1O2) were the primary factors in the photocatalytic degradation of BPA in the UV/PDS/FeOx systems. The main reactions of BPA in this system were deduced to be ß-bond cleavage, hydroxyl substitution reaction, hydrogen bond cleavage, and oxidation reaction. A trend of decreasing toxicity for the degradation intermediates of BPA was observed according to the toxicity investigations. The efficient degradation of BPA in UV/PDS/FeOx systems provided theoretical data for AOPs, which will improve the understanding of organic contaminants by FeOx in natural industry wastewater.

Long-infrared dual-wavelength linear-polarization-multiplexed confocal metalens based on an all-silicon dielectric.

The metalens has vast applications in biomedicine and industrial manufacturing due to their ultrathin structure and vital ability to manipulate the properties of light waves for long-infrared systems. However, it is difficult for metalens to achieve the confocal function with high focusing efficiency, wide wavelength bandwidth, and low structural complexity. Here, we propose and experimentally demonstrate an all-silicon dielectric metalens composed of arrays of minimalist meta-atoms with a single rectangular nanopillar arranged on a periodic square lattice substrate, which realizes the confocal function of the orthogonal-linear-polarized light with wavelengths of 10.6 µm and 9.3 µm, with focusing efficiencies of 64.94% and 60.03%, respectively. Also, it reveals nearly the diffraction-limited focusing performance. In addition, the metalens can realize precise long-infrared thermal imaging. Moreover, the proposed metalens is compatible with the standard complementary metal oxide semiconductor processes, which can effectively reduce the manufacturing cost and provide a feasible solution for developing planar integrated multifunctional micro-nanophotonic devices in the long-infrared field.